This invention relates to a burglar alarm for detecting the unauthorized opening of a door or window in a building. More particularly, the invention relates to a casing or housing for readily mounting on the frame of a sliding door or window containing a pressurized container which upon movement of the door or window against it causes gas under pressure to be discharged from the container through a sound emitting diaphragm valve thereby providing an audible alarm upon actuation by an unauthorized person.
Various alarm and locking systems for doors and windows involve elaborate locks and usually electronic alarm systems to resist entry and to raise alarm of such attempts. Such systems are static and cannot be utilized on other doors.
The disclosed invention is directed to a simple and mobile alarm that resists entry and provides a piercing alarm without reliance on an external power system.